Apparatus for extracting heat from gases under pressure



L. J. MARSHALL April 3, 1951 APPARATUS FOR EXTRACTING HEAT FROM GASES UNDER PRESSURE 3 Sheets-Sheet 1 Filed July 2, 1947 HoiGu Inlet IN VEN TOR.

Leonard J. Marshall Fig. I.

p l 3, 1951 J. MARSHALL 2,547,589

APPARATUS FOR EXTRACTING HEAT FROM GASES UNDER PRESSURE Filed Jul-y 2, 1947 s Sheets-Sheet 2 1 Superheored Steam I33 IN V EN TOR.

| Leonard J. Marshall Fig. 3. MMF

A ril 3, 1951 L. J. M ARSHALL APPARATUS FOR EXTRACTING HEAT FROM GASES UNDER PRESSURE 3 Sheets-Sheet S Filed July 2, 1947 INVENTOR.

4 Leonard J. Marshall BY miw Qur Fig.4.

Patented Apr. 3, 1951 APPARATUS FOR EXTRACTIN G HEAT FROM GASES UNDER PRESSURE Leonard J. Marshall, Anderson, Tenn., assignor to Combustion Engineering-Superheater, Inc., a corporation of Delaware Application July 2, 1947, Serial No. 758,503

3 Claims.

This invention relates to heat exchangers in which the heat is extracted from hot gases under pressure, and it has special reference to such exchangers wherein the extracted heat is emg c 2 by providing a gas passage from conduit into space 1 that radially separates the conduit from the outer shell or casing I. A gas outlet 8 is provided in that outer shell I adjacent the top ployed for purposes such a the generation of 5 head 2 and beneath the inlet 4. Hot gases under steam. pressure enter the inlet 4, pass downwardly An important object of the invention is the through inner conduit 5, then flow around the provision of a heat exchanger which is resistbottom end 6 of the conduit into space I -beant to substantial internal pressure by the gases tween the outer shell I- andconduit 5 and thence from which the heat is tobe extracted and in 10 upwardly-through the space 1 and out of the which the gas pressure resisting shell ismainexchanger casing through side outlet 8. tained at substantially the lowest temperature Heat absorbing surface such as groups or of the .gases leaving the heat absorbing surfaces. bundles of tubes 9, I0, H and I2 are placed Another object is to facilitate the manufacture within the conduit 5 to absorb vheat from the and assembly of such heat exchangers, gases flowing thereover and conduct it to fluid Further objects will appear from the following that is passed through thetubes. In the illusdescription of an illustrative embodiment of the trative disclosure there are four such bundles invention when taken in conjunction with the of tubes 9IUII-I2, although a different accompanying drawings wherein: number may be used. Each tube group or bundle Figure 1 is a vertical cross section of the imis here shown as comprising a multiplicity of proved heat exchanger taken on line I-l of parallel rows of tubes I3 bent back and forth Figures 2 and 3; transversely of the surrounding conduit 5 to form Figure 2 is a horizontal cross section of the the represented coils. The opposing tube ends same apparatus taken on line 22 of Figure l; in each of these bundles are connected intoan Figure 3 is a viewin front elevation showing inlet header I4 and ,into an outlet, header I5 the improved heat exchanger used as a steam for respective supply. and removal of a heat abboiler and indicating piping connections from sorbing fluid which is passed through the tubes. heat-receiving elements in the exchanger to a Preferably the exchangers inner casing or steam and water separating drum and to water conduit 5 is made up of a multiplicity of sections circulation pumps; and I6, I1, l8 and I9equalin number to the number Figure 4 is a side elevation of the same exof tube bundles. 9-,lllII-.-I2. These. several changer-boiler apparatus, as viewed from the sections are joined one to another in end-to-end right of Fig. 3, showing further piping connecrelation by expansion joints 20. In each of the tion details. bundles here designated 9--IflI II2 tube I The improved heat exchanger here illustrated sheets shown at 2! in Figs. 1 and 2 are placed comprises an upright shell I having top and at the bent portions 22 of the fluid-circulating bottom heads 2 and 3 capable of resisting the tubes I3 and are provided with holes for receiving internal pressure under which the heating gases those bent portions 22 thereby. maintaining flowing therethrough are delivered. In one approper relative spacing of the individual tubes .plication for which the disclosed apparatus has I3 in the bundle. Each pair of these tube sheets been designed; this delivery pressure is about 2| extends above and below the supported tube ten atmospheres (approximately 142 pounds per bundle (9, It, II or l2 to the expansionjoints I square inch) and the entering gases have a tem- 20 at the top and bottom of the associated conperature of the order of 1400 F. An in1et.4 duit section (I9, I8, I I or IE5). Each sheet 2| for the heating gases is provided in the top head is then bent to contact the exchangers inner Z and a gas conduit 5, which forms a seal with casing or conduit 5 and form a seal with the the top head around the juncture of inlet 4, wall of that casing. In this manner these tube with the head extends downwardly through the sheets 2| also serve as bafiles to keep the gases shell I. from short circuiting past the tube ends 22 where In this disclosure the inner gas conduit 5 is .50 the resistance to flow is relatively low. rectangular in cross section and its cross sec- Each of the tube bundle and easing section tional area is less than that of the surrounding assemblages 9-I9, I0-I8, I III and I2-l6 outer casing or shell I (see Fig. 2). This inner thus formed is supportedly positioned in the exconduit 5 terminates with its bottom end 6 at .changers outer. casing I through the mediumof a. spaced distance from the bottom head 3, therethe asscmblages inlet and outlet headers I4 and of these component assemblages 9I9,

.and II I5. Thus, in the case of assemblage II-II the tube bundle I I, tube sheets 2| and the surrounding section II of the exchangers inner casing 5 all derive their support from outer casing I through the inlet and outlet headers I4 and I5 for that assemblage.

As is best indicated by Fig. 2, each and every header I4 and I5 in the heat exchanger is closed at one end 23 within the shell I and extends through the opposite shell side at 24 ad acent the headers other end. Theclosed end 23-of each header is supported from the shell I as by a bracket 25 and each header is further supported by the shell where it passestherethrough at 24. At each point 24, moreover, there is provided means for hermetically sealing the joint between the header and the shell.

Each of the various conduit sections I9, I8, I1 and I6 together with its associated tube bundles 9, IG, II and I2 and set of headers I l-I5 thus forms a unit which may be completely assembled, welded and stress relieved in the fabricating shop. When, moreover, the heat exchanger is completely assembled the entire weight of each I9I8, III'I and I2IB will be carried by the outer shell through headers I lI5 in the unique man- 'ner just explained.

In the embodiment of Figs. 3 and 4, where the heat exchanger is to be used as a steam generator, the uppermost tube bundle 9 serves as a steaming unit, the next lower tube bundle It serves as a superheater unit, the next lower tube ibundle II serves as a steaming unit and the lowermost tube bundle I2 serves as an economizerunit. When so used as'a steam generator, a steam and water separating drum 25 is provided into which both of the steaming units 9 discharge. Preferably these steaming units. (first and third counting from the exchanger top) will be provided with forced circulation pumps 21, as representedin Figs. 3 and 4.

In the complete system of Figs. 3 and 4, downcomer tubes 28 connect the bottom of the steam. and water separating drum 26 with the suction side of pumps 21; other tubes 29 and 3G connect the inlet headers I4 for the exchangers steaming ,units I I and 9 respectively, with the discharge side of the pumps; riser tubes 3! and 32 respectively connect the outlet headers I5 of the exchanger steaming units II and 9 with the steam and water separating drum 26; and a saturated steam tube-.33 connects the steam and water drum withthe in et header Id of the superheater unit Ill. The outlet header I5 of this superheater unit I is connected by ip n to the point of use. The economizer unit .I Zreceives water from the boiler feed pump (not shown) via pipe 34 connected to its inlet header I4. The economizer. outlet header I is connectedby pipe 35 to the steam and water separating drum 26.

Circulation pumps 21 are driven by any suitable means, such as motors 36.

In operation, the hot gases from which the heat is to be extracted enter the heatexchan er through inlet 4 and thence pass downwardly successively through tube bun les 9. I. I! and [2 while givin up heat. Upon leaving the economizer unit tube bundle I2 the gases are cooled.

to their final ow temperature an the cool gases thencepass upwardly throu h the space I between the out r shell or casing I and the inner Iconduit or casing 5 to leave the h at exchan r 1 throueh outlet 8. In this ma ner the outer shell I'isexposed only to gases at theirfinal low temperature and the shell temperature approaches that of the cooled gases.

This is an advantage in that the strength of the metal in the shell I, due to increase in temperature, is impaired as little as possible. Moreover, any minor leakage through the walls or joints of inner conduit 5 into the surrounding space I between outer shell I and conduit 5 will have but a negligible influence upon the temperature of the relatively large mass of cool gases passing upwardly through said space when mixing therewith.

The economizer tube bundle I2 and the steaming tube bundles II and 9 are arranged with their inlet headers at the bottom and their discharge headers at the top. For the steaming units this may be'of importance in case of failure of the circulating pum s, because water will then flow by natural circulation, from the steam and water drum through the pump, which will be of the centrifugal type, thence through the steaming un ts and back to the drum. This circulation will be sufficient to protect the tubes of the steaming unit against ov rheating.

While the preferred embodiment of the invention has been shown and described, it will be un erstood that changes in construction, combination an arrangement of parts may be made without departing from the spirit and scope of the i vention as claimed.

I claim:

1. A heat exchanger for extracting heatfrom hot gases flowing therethrough under pressure com rising a vessel having a cylindrical shell and heads capable of resisting-the gas pressure internal y together with an inlet for the hot gases ,in one head and an outlet for the cooled gases in the shell ad acent sa d inlet head: a multi-section as conduit within the shell extending longitud nally thereof in radially spaced relation thereto and being open at one of its ends and joined at its other end to said inlet head thereby forming a connection with the gas inlet, said multi-section conduit extending through the shell continuously from the inlet head thereof to a location spaced from the opposite shell head whereby to provide a gas passage leading from the open conduit end into the space radially separating the conduit and shell, the sections of the conduit being joined transversely of the conduit by transverse expansion joints; a bundle of heat absorbing tubes within each of said sections made up of rows of tubes bent back and forth; an inlet and an outlet header for each of said tube bundles respectively receiving opposing ends of the heat absorbing tubes in the bundle rows and constituting mechanical supports for those tubes. each of said inlet and outlet headers passing throughopposite sides of the respective conduit section, each header being closed at one end and. passing adjacent its opposite 'open' end through the wall of said vessel shell to the exterior thereof; means supporting each header from the shell interior at the headers closed end; and means at the point of passage of each headers opposite end through the shell wall further supporting that header from the wall and sealing it with respect thereto.

2. In a heat exchanger for extractingheat from hot gases flowing therethrough under me. sure, the combination of a vessel having a cylindrical shell and heads capable of resisting the gas ressure internally together with an inlet for the hot gases in one head and an outlet for the cooled gases in the shell adjacent said inlet head thereof to a location spaced from the opposite shell head whereby to provide a gas passage leading from the open conduit end into the space radially separating the conduit and shell; transverse expansion joints securing said sections of the conduit one to another in end-to-end relation; a bundle of heat absorbing tubes within each conduit-section comprising rows of tubes bent back and forth transversely of the conduit; an inlet header and an outlet header for each of said tube bundles respectively receiving opposing ends of the heat absorbing tubes in the bundle rows and constituting mechanical supports for those tubes, said inlet and outlet headers being located respectively below and above the supported bundle and passing through opposite sides of the respective conduit section, each header being closed at one end and passing adjacent its opposite open end through the wall of said vessel shell to the exterior thereof; means supporting each header from the shell interior at the headers closed end; and means at the point of passage of each headers opposite end through the shell wall further supporting that header from the wall and sealing it with respect thereto.

3. In boiler apparatus for generating steam from hot gases flowing therethrough under pressure, the combination of a heat-exchanger having a cylindrical shell and heads capable of resisting the gas pressure internally together with an inlet for the hot gases in one head and an outlet for the cooled gases in the shell adjacent said inlet head; a multi-section gas conduit within the shell extending longitudinally thereof in radially spaced relation thereto and being open at one of its ends and joined at its other end to said inlet head thereby forming a connection with the gas inlet, said multi-section conduit extending from the inlet head through the shell and terminating at a spaced distance from the opposite shell head to provide a gas passage from the conduits open end into the space radially separating the conduit and shell; transverse expansion joints securing said sections of the conduit one to another in end-to-end relation; a bundle of heat absorbing tubes within each of said sections made up of rows of tubes bent back and forth transversely of the conduit; an inlet header and an outlet header for each of said tube bundles respectively f receiving opposing ends of the heat absorbing tubes in the bundle rows and constituting mechanical supports for the tubes, said inlet and outlet l'leaders being located respectively below and above the supported bundleand projecting through opposite sides of the respective conduit section, each header being closed at one.

end and passing adjacent its opposite open end through the wall of said drum shell to the exterior thereof; means supporting each header from the shell interior at the headers closed end; means fastening the opposite end of each header in sealed relation to the shell at the point of passage through the shell wall; a steam and water separating drum external to said heatexchanger shell and having a steam ofitake; means connecting said separator drum with the outlet headers of said tube bundles in the heatexchanger; a circulation pump connected at its suction side with the bottom of said separator drum and at its discharge side with the inlet headers of the'tube bundles; and means for driving said pump.

LEONARD J. MARSHALL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

